Advances in high energy astronomy from space

Observational techniques, derived through space technology, and examples of what can be learned from X-ray observations of a few astronomical objects are given. Astronomical phenomena observed include the sun, stellar objects, and galactic objects

A high energy astronomy overview

A technology assessment of extrasolar X-ray astronomy is presented. The role and significance of the Einstein Observatory is described

X-ray reflection collimator adapted to focus X-radiation directly on a detector Patent

X ray collimating structure for focusing radiation directly onto detecto

Axial Anomaly in the Presence of the Aharonov-Bohm Gauge Field

We investigate on the plane the axial anomaly for euclidean Dirac fermions in the presence of a background Aharonov--Bohm gauge potential. The non perturbative analysis depends on the self--adjoint extensions of the Dirac operator and the result is shown to be influenced by the actual way of understanding the local axial current. The role of the quantum mechanical parameters involved in the expression for the axial anomaly is discussed. A derivation of the effective action by means of the stereographic projection is also considered.Comment: 15 pages, Plain.TeX, Preprint DFUB/94 - 1

A FIRST DETERMINATION OF THE SURFACE DENSITY OF GALAXY CLUSTERS AT VERY LOW X--RAY FLUXES

We present the first results of a serendipitous search for clusters of galaxies in deep ROSAT-PSPC pointed observations at high galactic latitude. The survey is being carried out using a Wavelet based Detection Algorithm which is not biased against extended, low surface brightness sources. A new flux--diameter limited sample of 10 cluster candidates has been created from $\rm\sim 3 \, deg^2$ surveyed area. Preliminary CCD observations have revealed that a large fraction of these candidates correspond to a visible enhancement in the galaxy surface density, and several others have been identified from other surveys. We believe these sources to be either low--moderate redshift groups or intermediate to high redshift clusters. We show X-ray and optical images of some of the clusters identified to date. We present, for the first time, the derived number density of the galaxy clusters to a flux limit of $\rm 1\cdot 10^{-14} erg cm^{-2} s^{-1}$ (0.5--2.0 keV). This extends the $\log N$--$\log S$ of previous cluster surveys by more than one decade in flux. Results are compared to theoretical predictions for cluster number counts.Comment: uuencoded compressed Postscript, 7 pages including 4 figures. Accepted for publication in Ap. J. Letters

Results of a Sounding Rocket experiment to study celestial X-ray sources Final report

Sounding rocket experiment to study celestial X-ray source

A program of X-ray astronomy from sounding rocket Final report

X-ray astronomy from sounding rocket